Interleukin-2 (IL-2) is a cytokine and growth factor present in the CNS. Previous preliminary work has found IL-2 to be elevated in medication- free schizophrenic subjects. Since elaboration of central growth factors may have significant implications on the pathophysiology of schizophrenia, it was felt that conformation of this finding would be important. CSF samples from medicated and medication-free schizophrenic subjects and controls were assayed using ELISA for IL-2. It was found that the levels of IL-2 in the human CSF are at the lower detection limits of this assay, and, consequently, there was great variance in the values obtained. Since the assay we used was identical to that used in previous studies, our data suggest that reported IL-2 elevations may be methodological artifacts.